Human adenovirus-associated health risk in the recreational waters of the Yal-ku lagoon in the Mexican Caribbean.

The study objective was to evaluate human faecal contamination impacts in the Yal-ku lagoon in the Mexican Caribbean and to estimate adenovirus infection and illness risks associated with recreational exposure during water activities. A total of 20 water samples (10 from each site × two sites) (50 L) were collected monthly over a period of 12 months from two selected sampling sites in the swimming area of the Yal-ku lagoon. The occurrence of faecal-associated viruses was explored, and human adenovirus (HAdV) and pepper mild mottle virus (PMMoV) concentrations were quantified. A quantitative microbial risk assessment (QMRA) model was used to estimate exposure and subsequent adenovirus infection and illness risk for 1 h of swimming or snorkelling. Somatic and F + -specific coliphages occurred in 100% of the samples. Both HAdV and PMMoV were detected at a 60% frequency thereby indicating persistent faecal inputs. PMMoV concentrations (44-370 GC/L) were relatively lower than the concentrations of HAdV (64-1,000 GC/L). Estimated mean adenovirus risks were greater for snorkelling than for swimming by roughly one to two orders of magnitude and estimated mean illness risks for snorkelling were >32/1,000. Human faecal contamination is frequent in the Yal-ku lagoon, which is associated with human gastrointestinal illness.

Environmental Surveillance of SARS-CoV-2 RNA in Wastewater and Groundwater in Quintana Roo, Mexico.

The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater has been reported as a result of fecal shedding of infected individuals. In this study, the occurrence of SARS-CoV-2 RNA was explored in primary-treated wastewater from two municipal wastewater treatment plants in Quintana Roo, Mexico, along with groundwater from sinkholes, a household well, and submarine groundwater discharges. Physicochemical variables were obtained in situ, and coliphage densities were determined. Three virus concentration methods based on adsorption-elution and sequential filtration were used followed by RNA isolation. Quantification of SARS-CoV-2 was done by RT-qPCR using the CDC 2020 assay, 2019-nCoV_N1 and 2019-nCoV_N2. The Pepper mild mottle virus, one of the most abundant RNA viruses in wastewater was quantified by RT-qPCR and compared to SARS-CoV-2 concentrations. The use of three combined virus concentration methods together with two qPCR assays allowed the detection of SARS-CoV-2 RNA in 58% of the wastewater samples analyzed, whereas none of the groundwater samples were positive for SARS-CoV-2 RNA. Concentrations of SARS-CoV-2 in wastewater were from 1.8 × 103 to 7.5 × 103 genome copies per liter (GC l-1), using the N1 RT-qPCR assay, and from 2.4 × 102 to 5.9 × 103 GC l-1 using the N2 RT-qPCR assay. Based on PMMoV prevalence detected in all wastewater and groundwater samples tested, the three viral concentration methods used could be successfully applied for SARS-CoV-2 RNA detection in further studies. This study represents the first detection of SARS-CoV-2 RNA in wastewater in southeast Mexico and provides a baseline for developing a wastewater-based epidemiology approach in the area.

Occurrence of Pepper Mild Mottle Virus (PMMoV) in Groundwater from a Karst Aquifer System in the Yucatan Peninsula, Mexico.

The Yucatan Peninsula of Mexico hosts a karst aquifer system that is the only source of freshwater for the area; however, it is vulnerable to human-mediated contamination. Pepper mild mottle virus (PMMoV) is one of the most abundant RNA viruses associated with human feces, making it a viable indicator for tracking fecal pollution in aquatic environments, including groundwater. In this study, groundwater samples collected from a karst aquifer from fresh and brackish water locations were analyzed for fecal indicator bacteria, somatic and male F+ specific coliphages, and PMMoV during the rainy and dry seasons. Total coliform bacteria were detected at all sites, whereas Escherichia coli were found at relatively low levels <40 MPN/100 ml. The highest average concentrations of somatic and male F+ specific coliphages were 920 and 330 plaque forming units per 100 ml, respectively, detected in freshwater during the rainy season. PMMoV RNA was detected in 85% of the samples with gene sequences sharing 99-100% of nucleotide identity with PMMoV sequences available in GenBank. Quantification of PMMoV genome copies (GC) by quantitative real-time PCR indicated concentrations ranging from 1.7 × 101 to 1.0 × 104 GC/L, with the highest number of GC detected during the rainy season. No significant correlation was observed between PMMoV occurrence by season or water type (p > 0.05). Physicochemical and indicator bacteria were not correlated with PMMoV concentrations. The abundance and prevalence of PMMoV in the karst aquifer may reflect its environmental persistence and its potential as a fecal indicator in this karst aquifer system.

Planktonic cyanobacteria of the tropical karstic lake Lagartos from the Yucatan Peninsula, Mexico.

The tropical karstic lakes on the Mexican Caribbean Sea coast are numerous. However, there is an enormous gap of knowledge about their limnological conditions and micro-algae communities. In the present study, surface water samples were collected monthly from November 2007 to September 2008 to provide taxonomical composition and biovolume of planktonic cyanobacteria of the lake Lagartos from State of Quintana Roo, Mexico. Water temperature, pH, conductivity, salinity, soluble reactive phosphorus (SRP), dissolved inorganic nitrogen (DIN), and soluble reactive silica (SRSi) levels were also analyzed. A total of 22 species were identified. Chroococcales and Oscillatoriales dominated the phytoplankton assemblages during the study period. Chroococcus pulcherrimus, Coelosphaerium confertum, Cyanodyction iac, Phormidium pachydermaticum and Planktolyngbya contorta were recorded for the first time in Mexico. A surplus of DIN (mean value of 42.7 microM) and low concentrations of SRP (mean value of 1.0 microM) promoted the enhanced growth and bloom formation of cyanobacteria. The mean biovolume was 3.22 x 10(8) microm3/mL, and two biovolume peaks were observed; the first was dominated by Microcystis panniformis in November 2007 (7.40 x 10(8) microm3/mL), and the second was dominated by Oscillatoriaprinceps in April 2008 (6.55 x 10(8) microm3/mL). Water quality data, nitrates enrichment, and trophic state based on biovolume, indicated that Lagartos is a hyposaline, secondarily phosphorus-limited, and eutrophic lake, where the cyanobacteria flora was composed mainly by non-heterocystous groups.

Planktonic Cyanobacteria of the tropical karstic lake Lagartos from the Yucatan Peninsula, Mexico / Las cianobacterias planctónicas del lago tropical cárstico Lagartos de la Península de Yucatán, México

The tropical karstic lakes on the Mexican Caribbean Sea coast are numerous. However, there is an enormous gap of knowledge about their limnological conditions and micro-algae communities. In the present study, surface water samples were collected monthly from November 2007 to September 2008 to provide taxonomical composition and biovolume of planktonic cyanobacteria of the lake Lagartos from State of Quintana Roo, Mexico. Water temperature, pH, conductivity, salinity, soluble reactive phosphorus (SRP), dissolved inorganic nitrogen (DIN), and soluble reactive silica (SRSi) levels were also analyzed. A total of 22 species were identified. Chroococcales and Oscillatoriales dominated the phytoplankton assemblages during the study period. Chroococcus pulcherrimus, Coelosphaerium confertum, Cyanodyction iac, Phormidium pachydermaticum and Planktolyngbya contorta were recorded for the first time in Mexico. A surplus of DIN (mean value of 42.7µM) and low concentrations of SRP (mean value of 1.0µM) promoted the enhanced growth and bloom formation of cyanobacteria. The mean biovolume was 3.22X10(8)µm³/mL, and two biovolume peaks were observed; the first was dominated by Microcystis panniformis in November 2007 (7.40X10(8)µm³/mL), and the second was dominated by Oscillatoria princeps in April 2008 (6.55X10(8)µm³/mL). Water quality data, nitrates enrichment, and trophic state based on biovolume, indicated that Lagartos is a hyposaline, secondarily phosphorus-limited, and eutrophic lake, where the cyanobacteria flora was composed mainly by non-heterocystous groups.

Los lagos cársticos tropicales en la costa del Caribe mexicano son numerosos. Sin embargo, existe un enorme desconocimiento acerca de sus condiciones limnológicas y de las comunidades de microalgas que se desarrollan en ellos. El objetivo del presente estudio fue estudiar las condiciones limnológicas en las que crecen las poblaciones de cianobacterias planctónicas del lago Lagartos, Quintana Roo, México. Las recolectas se realizaron de forma mensual entre noviembre 2007 y septiembre 2008. Las especies fueron identificadas y su biovolumen determinado. Se midieron in situ la temperatura del agua, pH, conductividad y salinidad. También, se analizaron las concentraciones de fósforo reactivo soluble (SRP), nitrógeno inorgánico disuelto (DIN) y sílice reactivo soluble (SRSi). Se identificaron 22 especies de cianobacterias. Chroococcus pulcherrimus, Coelosphaerium confertum, Cyanodyction iac, Phormidium pachydermaticum y Planktolyngbya contorta fueron nuevos registros para México. Un exceso de DIN (valor promedio de 42.7µM) y bajas concentraciones de PRS (valor promedio de 1.0µM) promovieron la proliferación de cianobacterias. El biovolumen presentó dos picos: el primero en noviembre 2007, dominado por Microcystis panniformis (7.40X10(8)µm³/mL) y el segundo en abril 2008, representado por Oscillatoria princeps (6.55X10(8)µm³/mL). Los datos de calidad del agua, el enriquecimiento por nitratos y el estado trófico basado en el biovolumen, indican que Lagartos es un lago hiposalino, eutrófico, con limitación secundaria por fósforo, donde los crecimientos masivos de cianobacterias sin heterocitos fueron recurrentes.